The number of potential therapeutic targets in cancer biology has grown exponentially over the last twenty years with the advancement of the understanding of cancer genomics. In that same time, however, the number of approved therapies which target the most abundantly activated cancer-related genes has grown only marginally. Many cancer targets that are attractive from a biological perspective are considered intractable (“undruggable”) from a chemical standpoint. There is a growing understanding that these protein targets are not amenable to conventional drug discovery approaches, typically because they possess a relatively large contact area when interacting with other proteins (i.e., protein-protein interactions or “PPI”) or due to the fact that they possess a ligand that binds extremely tightly to the active site of the protein. An example of the latter case is found with proteins such as Ras which binds its ligand GTP with picomolar affinity making competition with potential drugs difficult. It is estimated that 75-80% of all existing targets are beyond the reach of the classical small molecule or biologic (protein) classes of therapeutics, which generally inhibit protein function by competitively binding to the protein's active site, among them a number of highly validated targets for cancer.
Allosteric modulators for such “undruggable” targets offer an attractive therapeutic solution. By definition, allosteric molecules bind to a site other than a protein's active site thereby changing the protein's conformation with a concomitant functional effect (e.g., inhibition, activation of a receptor, etc.). Additionally, among other advantages (1), allosteric modulation of target proteins has the added benefit of not having to rely on inhibition or competition with the binding of the natural ligand to the protein, which can result in unintended clinical side effects. However, it has been difficult to identify allosteric modulators using currently available conventional techniques. For example, structural information obtained from X-ray crystallography or NMR methods is limited for drug discovery purposes due to low throughput, sensitivity, non-physiological conditions, size of the protein amenable to the technique, and many other factors. What is needed, therefore, are techniques to identify agents capable of allosterically modulating the structure of a target protein rapidly and in a high-throughput manner.
Such techniques are provided herein by the disclosure of methods for identifying agents capable of allosterically binding to a target protein thereby altering its conformational structure.
Throughout this specification, various patents, patent applications and other types of publications (e.g., journal articles) are referenced. The disclosure of all patents, patent applications, and publications cited herein are hereby incorporated by reference in their entirety for all purposes.